Republican state Senator Steve Smith (R-Maricopa) says he will challenge freshman Rep. Tom O’Halleran (D-Sedona) in the sprawling eastern Arizona 1st District, which stretches all the way from the New Mexico-Colorado-Utah border to beyond the Phoenix metropolitan area in annexing half of Pinal County. The 1st District is highly marginal, but leans Democratic, though President Trump carried the seat by just over a percentage point.